CN112752829A - Fluidized bed process and catalyst system for fischer-tropsch conversion - Google Patents

Abstract

Disclosed is a method for performing Fischer-Tropsch (FT) synthesis to produce C₄ ⁺A process and catalyst system for hydrocarbons, such as gasoline boiling range hydrocarbons and/or diesel boiling range hydrocarbons. Advantageously, the catalyst system described herein has additional activity (in addition to FT activity) for in situ hydroisomerization and/or hydrocracking of wax produced from the distribution of hydrocarbons obtained from the FT synthesis reaction. This not only increases the hydrocarbons (e.g., C) available for transportation fuels_4‑19Hydrocarbons) yield, but also allows for alternative reactor types, such as fluidized bed reactors.

Description

Fluidized bed process and catalyst system for fischer-tropsch conversion

Cross Reference to Related Applications

This application claims priority to U.S. provisional application No. 62/711,103, filed on 27.7.2018, which is incorporated by reference in its entirety.

Technical Field

Aspects of the present invention relate to the use of a fluidized bed reactor in combination with a catalyst mixture or a dual-functional catalyst (bi-functional catalyst) for performing Fischer-Tropsch synthesis reactions in the production of liquid hydrocarbons, such as gasoline boiling-range hydrocarbons (gasoline boiling-range hydrocarbons) and/or diesel boiling-range hydrocarbons.

Background

The ongoing research into alternatives to crude oil for the production of hydrocarbon fuels is driven by a variety of factors. These include reduced petroleum reserves, higher anticipated energy demands, and increased concerns about greenhouse gas (GHG) emissions from non-renewable carbon sources. In view of the abundance of methane in natural gas reserves and in gas streams obtained from biological sources (biogas), methane has been the focus of many possible approaches for providing liquid hydrocarbons. A key commercial process for converting methane to fuel involves a first conversion step to produce synthesis gas (syngas), followed by a second, downstream fischer-tropsch (FT) conversion step.

As regards the first conversion step, known processes for the production of synthesis gas from methane include partial oxidation reforming (ATR) based on the exothermic oxidation of methane with oxygen and autothermal reforming (ATR). In contrast, Steam Methane Reforming (SMR) uses steam as an oxidant, making thermodynamics significantly different, not only because the generation of steam itself may require energy investments (energy investments), but also because reactions involving methane and water are endothermic. Recently, the use of carbon dioxide (CO) has also been proposed₂) As an oxidant for methane, so that Carbon (CO) in its most oxidized form is passed through₂) And it isMost reduced form of Carbon (CH)₄) To form the desired synthesis gas. This reaction has been referred to as "dry reforming" of methane, and because it is highly endothermic, the thermodynamics of dry reforming of methane is less favorable than ATR or even SMR. However, the stoichiometric consumption of 1 mole of carbon dioxide per mole of methane has the potential to reduce the total carbon footprint of liquid fuel production, which provides a "greener" consumption of methane.

In a second step involving FT conversion, hydrogen (H) is contained₂) And carbon monoxide (CO), the syngas undergoes successive C-O bond scission and C-C bond formation, with hydrogen incorporated. This mechanism provides for the formation of hydrocarbons, and in particular linear paraffins, having a distribution of molecular weights that can be controlled to some extent by varying the FT reaction conditions and catalyst properties. Such properties include the pore size and other characteristics of the support material. The choice of catalyst may otherwise affect the yield of FT products. For example, iron-based FT catalysts tend to produce more oxygenates (oxygenates), while ruthenium as the active metal tends to produce only paraffins.

At economic conversion levels to desired hydrocarbons, particularly gasoline boiling range hydrocarbons and/or diesel boiling range hydrocarbons, the FT reaction invariably results in the co-formation of higher molecular weight hydrocarbons that are solids at room temperature and are commonly referred to as "waxes". This is a result of the FT reaction chemistry according to which, in each carbon addition step, chain growth occurs with some finite probability to produce successively higher molecular weight molecules. The production of wax adds significant process complexity in terms of further processing requirements, such as converting the wax to the desired hydrocarbons in a separate hydrocracking step. Furthermore, the difficulties associated with removing wax by-products from the FT catalyst impose limitations on the possible types of reactors that may be used. That is, the problem of wax formation makes it impractical to use certain reactors that would otherwise be ideal for FT synthesis.

Summary of The Invention

Aspects of the invention and use of the catalyst system for producing C such as gasoline boiling range hydrocarbons and/or diesel boiling range hydrocarbons₄ ⁺The discovery of a process for hydrocarbons is relevant in that the catalyst system is active for catalyzing both (i) fischer-tropsch (FT) synthesis reactions and (ii) hydroisomerization and/or hydrocracking of wax for converting the wax into more desirable hydrocarbons that are not solids at room temperature. Such a catalyst system thus allows in situ dewaxing of the distribution of hydrocarbons produced by the FT synthesis reaction alone. This may advantageously overcome the need for a separate dewaxing step downstream of the FT synthesis reaction, such as a conventional FT wax hydrocracking step.

Furthermore, such catalyst systems broaden the possible types of reactors that can be used for the FT synthesis reaction. Importantly, a representative process may use a fluidized bed reactor (e.g., a bubbling fluidized bed reactor) that would not otherwise allow continuous removal (elutriation) of the positive C in the FT product in the absence of in situ dewaxing₂₀ ⁺Amount of hydrocarbons (in wax fraction). The low volatility of such hydrocarbons prevents their vaporization into the gaseous product stream leaving the bubbling fluidized bed of catalyst particles, which is necessary for operation of this reactor type. Advantages of using a fluidized bed reactor for the FT synthesis reaction include: excellent mixing and temperature uniformity, which are particularly beneficial in highly exothermic reaction environments; and effective gas/solid disengagement above the fluidized bed of catalyst particles.

In some embodiments, the catalyst system comprises an FT functional component and a dewaxing functional component, wherein these components are present in separate types of catalysts or are otherwise present in a single dual function catalyst. Under suitable reaction conditions as described herein, the catalyst system catalyzes both FT synthesis and dewaxing to provide FT products that are substantially free of wax (such as, for example, containing less than about 1 wt-% hydrocarbons that are solid at room temperature). In view of such catalyst systems, a further aspect of the present invention is relevant to the discovery that (i) H is used in the synthesis gas feed₂And the distributed FT synthesis reaction of CO to hydrocarbons and (ii) for the conversion of normal C by hydroisomerization and/or hydrocracking₂₀ ⁺Conversion of hydrocarbons to normal C₄-C₁₉Hydrocarbons or branches C₄-C₁₉The dewaxing reaction of hydrocarbons can be effectively carried out under the same set of conditions and in the same reactor. This can greatly simplify the FT synthesis reaction compared to conventional processes for carrying out the reaction, particularly in view of the separate dewaxing step required in such processes. Significant capital cost and/or operating cost advantages associated with the process and catalyst system of the present invention may thereby be realized.

These and other embodiments, aspects, and advantages associated with the present invention will be apparent from the detailed description that follows.

Detailed description of the invention

The expressions "wt-% and" mol-% "are used herein to designate weight percent and mole percent, respectively. For an ideal gas, "mol-%" is equal to a volume percentage.

As used herein, such as "C₄ ⁺Hydrocarbon and C₂₀ ⁺Hydrocarbon and C₄-C₁₉The term hydrocarbon "and the like refer to hydrocarbons having greater than 4 carbon atoms, hydrocarbons having greater than 20 carbon atoms, hydrocarbons having from 4 to 19 carbon atoms, and the like, respectively. Unless otherwise indicated, these terms do not imply that hydrocarbons having all carbon numbers according to the specified ranges must necessarily be present. Unless otherwise stated, such as by specifying "positive C₂₀ ⁺Hydrocarbon "otherwise such terms are intended to encompass all types of hydrocarbons (such as normal hydrocarbons, branched hydrocarbons, aromatic hydrocarbons, naphthenic hydrocarbons, olefins, etc.).

The terms "naphtha boiling range hydrocarbons" and "gasoline boiling range hydrocarbons" are meant to encompass hydrocarbons having a boiling point in C₅Hydrocarbon fractions of hydrocarbons boiling within the hydrocarbon characteristic of an initial (front end) distillation temperature of 35 ℃ (95 ° F) and a final distillation temperature of 204 ℃ (399 ° F). The term "jet fuel boiling range hydrocarbons" refers to a hydrocarbon fraction comprising hydrocarbons having boiling points within a front end distillation temperature of 204 ℃ (399 ° F) and an end distillation temperature of 271 ℃ (520 ° F). The term "diesel boiling range hydrocarbons" refers to a hydrocarbon fraction comprising hydrocarbons having boiling points within a front end distillation temperature of 204 ℃ (399 ° F) and an end distillation temperature of 344 ℃ (651 ° F). Thus, it is possible to provideBy "diesel boiling range hydrocarbons" is meant "jet fuel boiling range hydrocarbons," but also includes "heavy diesel boiling range hydrocarbons" having boiling points within a front end distillation temperature of 271 ℃ (520 ° F) and an end distillation temperature of 344 ℃ (651 ° F). The term "VGO boiling range hydrocarbons" refers to a hydrocarbon fraction comprising hydrocarbons having boiling points within a front end distillation temperature of 344 ℃ (651 ° F) and an end distillation temperature of 538 ℃ (1000 ° F). These front end distillation temperatures and end point distillation temperatures for hydrocarbon fractions such as naphtha boiling range hydrocarbons, gasoline boiling range hydrocarbons, jet fuel boiling range hydrocarbons and diesel boiling range hydrocarbons, which are also characteristic of the corresponding petroleum derived naphtha boiling range fraction, gasoline boiling range fraction, jet fuel boiling range fraction and diesel boiling range fraction, are determined according to ASTM D86, with the end point being the 95% recovery value.

The term "substantially" as used in relation to a given parameter in the phrases "substantially the same" or "substantially equal" is intended to encompass values or ratios that deviate by less than 5%. The term "substantially all" or "substantially all" means "at least 95%. The term "substantially complete" means "at least 95% complete".

Fluidized bed process for FT synthesis

Embodiments of the invention relate to methods for producing C₄ ⁺Fluidized bed process of hydrocarbons, C₄ ⁺Hydrocarbons are understood to include liquid hydrocarbons suitable for transportation fuels, such as gasoline, jet fuel and/or diesel fuel, or blending components for transportation fuels. Although C is₄The hydrocarbon butane is not a liquid in its pure form at room temperature, but it is still a suitable component of gasoline. A representative process involves feeding H in a syngas feed in a fluidized bed reactor containing a catalyst mixture or dual-function catalyst and operating under Fischer-Tropsch (FT) reaction conditions₂And CO to hydrocarbons provided in the FT products, including C₄ ⁺Hydrocarbons (i.e., at least some hydrocarbons having four or more carbon atoms). These C₄ ⁺The hydrocarbons include those in a distribution of hydrocarbons obtained from conversion by an FT synthesis reaction, which distribution may also initially includeComprising a positive C₂₀ ⁺A wax fraction of hydrocarbons (i.e., at least some normal or straight chain hydrocarbons having 20 or more carbon atoms, which are thus solid at room temperature), as described above. These C's in the FT product₄ ⁺The hydrocarbons may also include those in the distribution obtained from the FT synthesis, but after having been further converted by hydroisomerization and/or hydrocracking due to the catalytic activity provided by the catalyst system for these additional reactions.

Advantageously, it has been found that the catalyst system as described herein is additionally effective for the hydroisomerisation and/or hydrocracking of the wax fraction obtained from FT synthesis under conditions suitable for conversion by FT synthesis reactions. For example, the catalyst system may result in positive C₂₀ ⁺In situ conversion of at least a portion of the hydrocarbons to normal C₄-C₁₉Hydrocarbons or branches C₄-C₁₉Hydrocarbons (i.e., converted to normal or branched chain hydrocarbons, at least some of which have from 4 to 19 carbon atoms). This additional activity allows the possibility of providing FT products from a single reaction stage with in situ dewaxing, such that the FT products contain little or no wax (such as less than about 1 wt-% wax, or less than about 0.5 wt-% wax). Thus, a conventional separate dewaxing step can be avoided.

A further advantage of the catalyst system, which can significantly reduce or eliminate wax in a single reaction stage, is the possibility of carrying out the FT synthesis reaction in a fluidized bed reactor. Although this reactor type is generally not suitable for conventional FT synthesis because the solid wax fraction is difficult to elutriate, a process as described herein operating without any substantial net yield of wax can take advantage of the advantages of a fluidized bed in terms of its temperature homogeneity and good mixing characteristics, resulting in improved product quality control. The fluidization may be by including H₂And CO, is established by flowing the synthesis gas upward through a catalyst mixture or bed of solid particles of dual-function catalyst. Any recycled portion of the syngas feed and optionally the FT product (as described below) may be used as fluidizing gas, or may otherwise be combined with supplemental fluidizationA gas (e.g., an inert gas such as nitrogen) is used in combination to increase the superficial velocity (superficial velocity) of the fluidizing gas. Depending on the superficial velocity, in combination with all other variables that control the fluid dynamics of the reaction system (including gas density, particle density and particle size), a variety of fluidization regimes of the bed can be achieved. More specifically, in order to increase the superficial velocity, these schemes include a fixed Fluidized Bed, a bubble-free Fluidized Bed (bubbly Fluidized Bed), a bubbling Fluidized Bed, a slugging Fluidized Bed (slugging Fluidized Bed), a turbulent Fluidized Bed (turbulent Fluidized Bed), or a fast Fluidized Bed, and are described, for example, in Wen, C.Y ("Flow registers and Flow Models for Fluidized Bed Reactors," recovery adv. eng.ang. anel.chem.react.syst. (1984):256- > 290). A circulating fluidized bed system may also be used. Preferably, the fluidized bed reactor is operated with a fixed fluidized bed, a bubble-free fluidized bed, a bubbling fluidized bed or a slugging fluidized bed of solid particles of the catalyst mixture or the dual-function catalyst. More preferred is a bubbling fluidized bed.

FT products are typically removed or withdrawn from the reactor as a continuous vapor stream. For example, FT product may be removed from the catalyst mixture or the fluidized bed of the dual-function catalyst in an expanded solids removal section (expanded solids separation section) above the fluidized bed. More specifically, the disengagement section may be configured as a section of reactor diameter or cross-sectional area that is enlarged relative to the diameter or cross-sectional area of the fluidized bed. The height of such an enlarged disengagement section may extend to or above the Transport Disengagement Height (TDH) to promote disengagement of substantially all of the FT products from substantially all of the solid particles of the catalyst bed.

Other gas-solids separation devices (e.g., mechanical devices such as filters, cyclones, etc.) may be used instead of, but preferably in combination with, the enlarged solids disengagement section. Such a device may be used within the section or otherwise outside the section after disengagement and thus acts on the disengaged FT products. For example, one or more cyclones may be used within the disengagement section to increase the efficiency or extent of gas-solids disengagement. Effective disengagement, whether accompanied by a separation device or not, does not exclude the presence of small amounts of solid particles entrained in the FT product, and in particular the presence of fine particles of catalyst resulting from mechanical breakage or attrition. Such fine solid particles may be more completely removed in a further separation step, for example using a filter with a sufficiently small pore size, such as a microfilter.

Thus, a representative fluidized bed process for carrying out the FT synthesis reaction may include including H₂And CO, flows through the catalyst mixture or bed of solid particles of the dual-function catalyst, thereby causing fluidization of the bed. The catalyst mixture or dual-function catalyst is active for catalyzing at least two types of reactions under reaction conditions corresponding to the FT reaction conditions used in the fluidized bed reactor where the syngas and solid particles contact. These reactions, namely (i) the reaction of H by Fischer-Tropsch (FT) synthesis₂And a distribution of CO to hydrocarbons, wherein the distribution includes a distribution including positive C₂₀ ⁺An initial wax fraction of hydrocarbons, and (ii) by normal C₂₀ ⁺Hydroisomerization and/or hydrocracking of hydrocarbons will at least a portion, but preferably a substantial amount (such as at least about 75 wt-%) of n-C₂₀ ⁺Conversion of hydrocarbons to normal C₄-C₁₉Hydrocarbons or branches C₄-C₁₉A hydrocarbon. Advantageously, the activity towards the catalytic reactions (i) and (ii) provides in combination a catalyst comprising C₄ ⁺Hydrocarbons but with a significantly reduced amount of wax relative to the amount of wax produced by the FT synthesis reaction alone, for example, FT products comprising less than about 5 wt-%, or even less than about 1 wt-%, of hydrocarbons that are solid at room temperature. The fluidised bed process may also include disengaging substantially all of the FT products from substantially all of said solid particles, as hereinbefore described. Following the disengagement of the FT product, it may be subjected to cooling to condense the liquid fraction of the product (comprising hydrocarbons) and optionally to separate these hydrocarbons (e.g., by fractionation) to resolve (resolve) one or more product fractions, such as comprising all or substantially all of the gasoline boiling range hydrocarbons, jet fuel boilingThose product fractions of the range hydrocarbons, diesel boiling range hydrocarbons or VGO boiling range hydrocarbons.

Catalyst system providing both FT conversion activity and dewaxing activity

The catalyst system used to provide activity for both FT conversion and in situ dewaxing (hydroisomerization and/or hydrocracking) may comprise a catalyst mixture containing both catalyst types or other dual-function catalyst containing both types of functional components. In the case of a catalyst mixture, the catalyst type may be both a fischer-tropsch (FT) catalyst and a dewaxing catalyst, and optionally one or more other catalyst types. Likewise, in the case of a dual-function catalyst, the functional components may be both the FT functional component and the dewaxing functional component, and optionally one or more other types of functional components. The catalyst types of the catalyst mixture or the functional components of the other bifunctional catalysts may be present in equal or substantially equal weight ratios. For example, (i) the FT catalyst and (ii) the dewaxing catalyst may be present in the catalyst mixture in a weight ratio of (i) to (ii) of about 1: 1. Additionally, (i) the FT functional component and (ii) the dewaxing functional component may be present in the bifunctional catalyst in a weight ratio of (i) to (ii) of about 1: 1. In general, however, these weight ratios may vary, for example the weight ratio of (i) to (ii) in each case may be from about 10:1 to about 1:10, such as from about 5:1 to about 1:5, or from about 3:1 to about 1: 3.

The FT functional component of the FT catalyst or other dual function catalyst of the catalyst mixture may comprise one or more FT active metals or metals suitable for catalysing the FT synthesis reaction under reaction conditions as described herein. Such FT active metals include transition metals selected from cobalt (Co), iron (Fe), ruthenium (Ru) and nickel (Ni). Preferred FT catalysts or FT functional components comprise at least about 10 wt-% transition metal, and typically at least about 15 wt-% transition metal (e.g., from about 10 wt-% to about 40 wt-% or from about 15 wt-% to about 30 wt-% transition metal, such as Co). In the case of the FT functional component of the dual-function catalyst, such dual-function catalyst as a whole may comprise a lower amount of such transition metal, such as an amount of at least about 3 wt-% (e.g., from about 3 wt-% to about 30 wt-%), and typically an amount of at least about 5 wt-% (e.g., from about 5 wt-% to about 25 wt-%), based on the weight of the dual-function catalyst. Such transition metals, whether present in the FT catalyst or in the FT functional component, may be disposed on or deposited on a solid support, which is intended to encompass catalysts in which the active metal is on the surface of the support and/or within the porous internal structure of the support. Thus, in addition to the FT active metal, representative FT catalysts and FT functional components may also include a solid support, with exemplary solid supports including one or more metal oxides, such as those selected from the group consisting of alumina, silica, titania, zirconia, magnesia, strontium oxide, and the like. The solid support for the FT catalyst or FT functional component may comprise all or substantially all (e.g., greater than about 95 wt-%) of one or more of such metal oxides. Preferred FT catalysts or FT functional components comprise the transition metal cobalt (Co) in the above-described amounts (e.g., at least about 10 wt-%) on a support comprising alumina (aluminum oxide).

As described above, representative catalyst mixtures or bifunctional catalysts are advantageously employed for positive C₂₀ ⁺Hydroisomerization and/or hydrocracking of hydrocarbons is also a characteristic of activity for converting waxes (i.e., converting straight chain hydrocarbons that are solid at room temperature to branched chain and/or lower carbon number hydrocarbons that are not solid at room temperature). In view of this activity, the second catalyst of the catalyst mixture may be referred to as a dewaxing catalyst, or the second component of the dual-function catalyst may be referred to as a dewaxing functional component. Examples of such dewaxing catalysts or dewaxing functional components include at least one dewaxing-active (e.g. hydroisomerisation-active and/or hydrocracking-active) metal suitable for catalytic dewaxing reactions under the same reaction conditions as used for catalytic FT synthesis reactions. The dewaxing active metal may be disposed on or deposited on a solid support, which is intended to encompass catalysts in which the active metal is on the surface of the support and/or within the porous internal structure of the support. Representative dewaxing active metals may be selected from groups 12 to 14 of the periodic table, such as from group 13 or group 14 of the periodic table. A particular dewaxing active metal is gallium. The at least one dewaxing active metal can be present in an amount of, for example, from about 0.1 wt-% to about 3 wt-%, or from about 0.5 wt-% to about 2 wt-%, based on the weight of the dewaxing catalyst or dewaxing functional component. If a combination of dewaxing active metals is used, such as a combination of metals selected from groups 12-14 of the periodic table, such metals may be present in combined amounts within these ranges, based on the weight of the dewaxing catalyst or dewaxing functional component. In the case of the dewaxing functional component of the dual-function catalyst, such dual-function catalyst as a whole may comprise such dewaxing active metal in relatively low amounts, such as in an amount of from about 0.03 wt-% to about 2 wt-%, or from about 0.1 wt-% to about 1 wt-%, based on the weight of the dual-function catalyst. Typically, the dewaxing catalyst or dewaxing functional component may not contain a metal other than the dewaxing active metals described above (e.g., not containing a metal other than metals of groups 12 to 14 of the periodic table in such an amount or combined amount, not containing a metal other than metals of groups 13 or 14 of the periodic table in such an amount or combined amount, or not containing a metal other than gallium in such an amount or combined amount) in an amount or combined amount based on the weight of the dewaxing catalyst or dewaxing functional component (or optionally based on the weight of the dual function catalyst as a whole). Preferably, the dewaxing catalyst or dewaxing functional component (or optionally the dual function catalyst as a whole) does not comprise a metal other than the dewaxing active metal described above (e.g. does not comprise a metal other than a metal of groups 12 to 14 of the periodic table, does not comprise a metal other than a metal of group 13 or group 14 of the periodic table, or does not comprise a metal other than gallium) on the support.

In addition to the dewaxing active metal, representative dewaxing catalysts and dewaxing functional components may also comprise a solid support, particularly a solid acidic support, to promote hydrocracking activity. The acidity of the support can be adjusted, for example, by adjusting the pH at from 275 ℃ (527 ° F) to 500 ℃ (932 °)F) Is determined from the temperature range of (TPD) of the ammonia-saturated sample of the support, the temperature exceeding the temperature at which the ammonia is physically adsorbed (physisorb), for a certain amount of ammonia. The amount of acidic sites is in millimoles of acidic sites per gram (mmol/g) of support, thus corresponding to the number of millimoles of ammonia desorbed per gram of support in this temperature range. Representative solid supports include zeolitic molecular sieves or non-zeolitic molecular sieves and have acid sites of at least about 15mmol/g (e.g., from about 15mmol/g to about 75mmol/g), or at least about 25mmol/g (e.g., from about 25mmol/g to about 65mmol/g), as measured by ammonia TPD. In the case of zeolite molecular sieves, the acidity is silica with alumina (SiO)₂/Al₂O₃) As a function of the molar framework ratio, and in embodiments in which the solid support comprises a zeolitic molecular sieve (zeolite), the silica to alumina molar framework ratio thereof may be less than about 60 (e.g., from about 1 to about 60), or less than about 40 (e.g., from about 5 to about 40). A particular solid support may comprise one or more zeolitic molecular sieves (zeolites) having a structure type selected from the group consisting of FAU, FER, MEL, MTW, MWW, MOR, BEA, LTL, MFI, LTA, EMT, ERI, MAZ, MEI and TON, and preferably one or more selected from FAU, FER, MWW, MOR, BEA, LTL and MFI. The Structure of zeolites having these and other Structure Types is described in Meier, W.M, et al, Atlas of Zeolite Structure Types, 4 th edition, Elsevier: Boston (1996) and additional references are provided. Specific examples include Y-type zeolite (FAU structure), X-type zeolite (FAU structure), MCM-22(MWW structure), and ZSM-5(MFI structure), of which ZSM-5 and beta-type zeolite (BEA structure) are exemplary.

The solid support other than zeolitic molecular sieves and non-zeolitic molecular sieves includes metal oxides such as any one or more of silica, alumina, titania, zirconia, magnesia, calcia, strontia, and the like. In representative embodiments, the solid support may comprise (i) a single type of zeolitic molecular sieve, (ii) a single type of non-zeolitic molecular sieve, or (iii) a single type of metal oxide, wherein (i), (ii), or (iii) is present in an amount greater than about 75 wt-% (e.g., from about 75 wt-% to about 99.9 wt-%) or greater than about 90 wt-% (e.g., from about 90 wt-% to about 99 wt-%), based on the weight of the dewaxing catalyst or dewaxing active functional component (or optionally based on the weight of the bifunctional catalyst as a whole). Other components of the carrier, such as binders and other additives, may be present in minor amounts, such as in an amount of less than about 10 wt-% (e.g., from about 1 wt-% to about 10 wt-%), or a combined amount, based on the weight of the dewaxing catalyst or dewaxing-active functional component (or optionally based on the weight of the bifunctional catalyst as a whole). An exemplary dewaxing catalyst or dewaxing functional component comprises gallium as the dewaxing active metal, which is present on a support comprising or may consist essentially of ZSM-5 in an amount as described above (e.g., from about 0.5 wt-% to about 2 wt-%, such as about 1 wt-%, based on the weight of the dewaxing catalyst). Representative silica to alumina molar framework ratios for ZSM-5 are described above. In yet further embodiments, the dewaxing catalyst or dewaxing functional component can comprise a solid support, such as a solid acidic support as described above, without any dewaxing active metal (e.g., gallium) as described above.

In general, a representative catalyst mixture may comprise: (i) an FT catalyst comprising one or both of (a) one or more FT active metals and (b) an FT catalyst support comprising one or more metal oxides; and (ii) a dewaxing catalyst comprising one or both of (a) one or more dewaxing active metals and (b) a solid acidic support. A representative bifunctional catalyst may comprise: (i) an FT functional component comprising: (a) one or both of one or more FT active metals and (b) one or more metal oxides; and (ii) a dewaxing functional component comprising one or both of (a) one or more dewaxing active metals and (b) a solid acidic carrier. In either case of the catalyst mixture or the dual-function catalyst, (i) and (ii) may be present in a weight ratio as described above (e.g., from about 3:1 to about 1: 3).

FT Synthesis reaction, conditions and Performance in the case of in situ dewaxing

In an FT reactor (e.g. a fluidised bed reactor), H in the synthesis gas product is synthesized according to a Fischer-Tropsch (FT) synthesis reaction₂And at least a portion of the CO is converted to hydrocarbons, the fischer-tropsch synthesis reaction can be summarized as:

(2n+1)H₂+n CO→C_nH_2n+2+n H₂O。

thus, the conditions in the FT reactor are suitable for the synthesis of hydrocarbons according to the reaction, including C, which can be used as a liquid fuel or as a blending component of a liquid fuel₄ ⁺A hydrocarbon. In representative embodiments, FT reaction conditions (suitable for catalyzing both FT synthesis and dewaxing reactions) may include temperatures in the range from about 121 ℃ (250 ° F) to about 399 ℃ (750 ° F) or from about 193 ℃ (380 ° F) to about 316 ℃ (600 ° F). Other FT reaction conditions can include from about 689kPa (100psig) to about 3.44MPa (500psig), or from about 1.38MPa (200psig) to about 2.76MPa (400psig) gauge pressure.

The FT catalysts and FT reaction conditions described herein are generally suitable for obtaining at least about 20% (e.g., from about 20% to about 99% or from about 20% to about 75%), at least about 30% (e.g., from about 30% to about 95% or from about 30% to about 65%) or at least about 50% (e.g., from about 50% to about 90% or from about 50% to about 85%) of H₂And/or conversion of CO (H)₂Conversion or CO conversion). These FT conversion levels may be based on H, taking into account FT synthesis reaction chemistry₂Conversion or CO conversion, depending on the reactants in the syngas feed, which are stoichiometrically limited. Preferably, these FT conversion levels are based on CO conversion. These FT conversion levels may be based on the "per-pass" conversion achieved in a single pass through the FT reactor, or otherwise the overall conversion achieved by returning a recycled portion of the FT products to the FT reactor, as described in more detail below.

By adjusting the FT reaction conditions (e.g., FT reaction temperature and/or pressure) described above, and/or adjusting the Weight Hourly Space Velocity (WHSV), a desired H in the FT reactor may be achieved₂Conversion and/or CO conversion. FT reaction conditions may include Weight Hourly Space Velocity (WHSV), which is typically from about 0.01h^-1To about 10h^-1Typically from about 0.05h^-1To about 5h^-1And often from about 0.3h^-1To about 2.5h^-1. As understood in the art, WHSV is the weight flow of the total FT feed, e.g., syngas feed, any recycled portion of FT products, and any co-feed (co-feed) (e.g., secondary fluidizing gas) to the reactor divided by the weight of catalyst in the reactor and represents the equivalent catalyst bed weight of the total feed stream processed per hour. WHSV is related to the inverse of the reactor residence time. The conversion level (e.g., CO conversion) can be increased, for example, by increasing the pressure and decreasing the WHSV, both of which have the effect of increasing the reactant concentration and reactor residence time. The FT reaction conditions may optionally include returning a recycled portion of the FT products exiting the FT reactor to the FT feed for combination with the FT feed, or otherwise to the FT reactor itself. Recycle operation allows operation at relatively low "per pass" conversion through the FT reactor while achieving high overall conversion due to recycle. In some embodiments, such low per pass conversion may advantageously limit high molecular weight hydrocarbons (e.g., positive C)₂₀ ⁺Hydrocarbons) that may be produced as part of the distribution of hydrocarbons obtained from the FT synthesis reaction.

Preferably, however, the FT reaction conditions include little or even no FT product recycle. For example, the FT reaction conditions may include a weight ratio of recycled FT products to syngas feed (and any co-feeds) (i.e., a "recycle ratio") of generally less than about 1:1, typically less than about 0.5:1, and often less than about 0.1:1, where the recycled FT products and syngas feed (and any co-feeds) together provide the total FT feed. For example, the recycle ratio may be 0, which means that FT product recycle is not used such that the single pass conversion equals the total conversion. With such low recycle ratio, relatively high single pass H, in view of process efficiency and economics₂Conversion or CO conversion, such as at least about 50% (e.g., from about 5)0% to about 95%), at least about 70% (e.g., from about 70% to about 92%), or at least about 80% (e.g., from about 80% to about 90%) is desired. As the per pass conversion level increases, the distribution of hydrocarbons in the FT product is shifted to a distribution of hydrocarbons with increasing numbers of carbon atoms. This is in reducing light C₁-C₃Is advantageous in terms of the yield of hydrocarbons, the light C₁-C₃The hydrocarbons having less than desired C₄ ⁺The value of liquid hydrocarbons. In some embodiments, C₁-C₃Hydrocarbon yield ("gaseous hydrocarbon yield"), or conversion to C in the net FT product removed from the reactor (excluding any recycle fraction) in the CO in the syngas feed (and any CO-feed) to the FT reactor₁-C₃The portion of total carbon of the hydrocarbons is less than about 30% (e.g., from about 1% to about 30%) or even less than about 20% (e.g., from about 3% to about 20%).

Advantageously, in the absence of FT product recycle, compression costs are saved and the overall process design of the integrated process is simplified. There is a need to increase the per pass conversion and the distribution of hydrocarbons for the FT synthesis reaction towards a distribution of hydrocarbons with an increased number of carbon atoms (including the undesirable positive C)₂₀ ⁺Hydrocarbons), it is understood that aspects of the invention relate to the discovery of compounds derived from these ortho-carbons₂₀ ⁺In situ conversion of hydrocarbons to normal C₄-C₁₉Hydrocarbons and/or branches C₄-C₁₉Important advantages of hydrocarbon production are relevant. These hydrocarbons produced by the dewaxing reaction beneficially contribute to the yield of the desired naphtha boiling range hydrocarbons, jet fuel boiling range hydrocarbons, and/or diesel boiling range hydrocarbons in the FT product. As described above, the necessary dewaxing activity may be provided by a separate dewaxing catalyst or the dewaxing functional component of the dual function catalyst. In situ dewaxing thus advantageously converts C of FT synthesis reaction₄ ⁺Some or all of a wax fraction of hydrocarbons, where the wax fraction refers to hydrocarbons that are solid at room temperature (e.g., including normal C)₂₀ ⁺Hydrocarbons). In particular, the wax stage is based on reactions involving or possibly consisting of hydroisomerization and/or hydrocracking reactionsIs converted into C in situ₄-C₁₉A hydrocarbon. In the absence of such conversion, the wax fraction would not only represent a loss in yield of hydrocarbons having greater utility as liquid fuels, but would also present a serious problem in causing detrimental wax accumulation within the reactors and process piping, in addition to the difficulties associated with the transportation and blending of the final liquid product.

As described above, the dewaxing functional component of the dewaxing catalyst or dual function catalyst is preferably for positive C₂₀ ⁺Active in hydrocracking and/or hydroisomerisation of hydrocarbons, said normal C₂₀ ⁺Hydrocarbons may be formed as a result of the FT synthesis reaction. These hydrocarbons characteristic of solid waxes along with C more suitable as a component of liquid fuels₄-C₁₉Hydrocarbons are caused by the carbon number distribution of normal hydrocarbons produced by FT reaction chemistry. As understood in the art, hydroisomerization refers to the reaction of normal hydrocarbons in the presence of hydrogen to produce branched chain hydrocarbons. Hydrocracking refers to the reaction of hydrocarbons with hydrogen to produce hydrocarbons having a lower number of carbon atoms and therefore a lower molecular weight. Hydroisomerization is beneficial for improving hydrocarbons (e.g., C) having a lower number of carbon atoms and useful as a component of liquid fuels₄-C₁₉Hydrocarbons) that may be present in the FT product. These properties include a higher octane number (e.g., a research octane number and/or a motor octane number) of the naphtha boiling range hydrocarbons present in the FT product relative to a reference FT product that would otherwise be obtained in the absence of a dewaxing catalyst or the dewaxing functional component of the dual-function catalyst, and also include a reduced pour point of the diesel boiling range hydrocarbons present in the product. Hydrocracking is beneficial because of its overall effect on the distribution of hydrocarbons otherwise obtained from the FT synthesis reaction alone, such as the hydrocarbons in the reference FT product. In particular, hydrocracking is beneficial for reducing the positive C present in the FT product₂₀ ⁺Weight percent of hydrocarbons and possibly eliminating the presence of positive C in the FT product₂₀ ⁺A hydrocarbon. As used herein, a "reference FT product" is dewaxed in the absence of a dewaxing catalyst or a dual-function catalystProducts obtained with all the operating variables except the functional components being identical.

Since hydrogen is required for both the hydroisomerization and hydrocracking reactions, in a preferred embodiment, this hydrogen is present in the syngas feed or the total FT feed in stoichiometric excess of the amount required for the FT synthesis reaction. Optionally, the total FT feed may include a supplemental source of hydrogen, which may also serve as a secondary fluidizing gas. Preferably, however, no supplemental source of hydrogen is used, such that the hydrogen present in the syngas feed or the total FT feed (optionally including the hydrogen present in the recycle portion) is sufficient to carry out the FT synthesis reaction and dewaxing. According to some embodiments, hydrogen is present in the syngas feed or the total FT feed in a concentration of at least about 20 mol-% (e.g., from about 20 mol-%) to about 75 mol-%), at least about 30 mol-% (e.g., from about 30 mol-%) or at least about 40 mol-% (e.g., from about 40 mol-%) regardless of whether a supplemental hydrogen source is used. Representative sources of supplemental hydrogen, if used, are hydrogen that has been purified (e.g., by PSA or membrane separation) or impure hydrogen (e.g., syngas).

The dewaxing function of the dewaxing catalyst or dual function catalyst is generally suitable for achieving positive C, as described herein and under the FT reaction conditions described herein₂₀ ⁺Hydrocarbons (e.g. n-C)₂₀-C₆₀Hydrocarbons) at least about 80% (e.g., from about 80% to about 100%), at least about 85% (e.g., from about 85% to about 98%), or at least about 90% (e.g., from about 90% to about 95%). Because this conversion occurs in situ, such conversion levels can be determined (calculated) using the reference FT products, as described above, and more particularly, by comparing the positive C obtained in the reference FT products₂₀ ⁺The amount of hydrocarbon is in accordance with the normal C obtained using the dewaxing catalyst or the dewaxing function component of the dual-function catalyst₂₀ ⁺The amount of hydrocarbons is determined (calculated).

Such high conversion levels are important for improving the quality of the FT product, particularly as regards its transportability as a liquid fuel without the need for separation or conversion of solid waxThe ability to transport (e.g., via a conduit). Positive C compared to the operation of the FT synthesis reactor without the dewaxing catalyst or the dewaxing functional component of the dual-function catalyst (i.e., compared to the yield when determined using a reference FT product), positive C₂₀ ⁺Conversion of hydrocarbons to lower molecular weight C₄-C₁₉The conversion of hydrocarbons also increases the overall yield of these hydrocarbons. Preferably, at least about 75% (e.g., from about 75% to about 100%), at least about 85% (e.g., from about 85% to about 98%), or at least about 90% (e.g., from about 90% to about 97%) of the positive C in the FT product₂₀ ⁺The hydrocarbons being converted to C₄-C₁₉Hydrocarbons otherwise of positive C₂₀ ⁺Hydrocarbons will be present in the reference FT product as described herein. That is, from positive C₂₀ ⁺C of in situ conversion of hydrocarbons₄-C₁₉The hydrocarbon yield is within these ranges. Preferably, the FT product comprises less than about 2 wt-% or even less than about 1 wt-% of hydrocarbons that are solids at room temperature (e.g., normal C)₂₀ ⁺Hydrocarbons). In representative embodiments, the positive C is due to the use of a dewaxing catalyst or a dewaxing functional component of a dual function catalyst₂₀ ⁺The hydrocarbons are converted (e.g., at complete or substantially complete conversion and/or within the conversion ranges given above) with (i) a yield of isoparaffins (branched hydrocarbons) from about 25% to about 70% or from about 40% to about 60%, (ii) a yield of aromatic hydrocarbons from about 10% to about 35% or from about 15% to about 25%, (iii) a yield of gasoline boiling range hydrocarbons from about 50% to about 95% or from about 70% to about 90%, (iv) a yield of diesel boiling range hydrocarbons from about 5% to about 45% or from about 10% to about 30%, and/or (v) a yield of VGO boiling range hydrocarbons of less than about 1% or less than about 0.5%. These yields are referred to as positive C₂₀ ⁺The percentage of total carbon in the hydrocarbons that would otherwise be obtained in the reference FT product as described herein is converted to these components in the FT product obtained with the use of the dewaxing or dual function components of the dewaxing catalyst.

Advantageously, isoparaffins improve the quality of diesel boiling range hydrocarbons by lowering both the pour and cloud points of the fraction. Isoparaffins and aromaticsBoth hydrocarbons improve the quality of this fraction by increasing the octane number (e.g., research octane number and/or motor octane number) of the gasoline boiling range hydrocarbons. In representative embodiments, from positive C₂₀ ⁺The gasoline boiling range hydrocarbons obtained in the conversion of hydrocarbons that are otherwise present in the reference FT product as described herein have a research octane number of at least about 75 (e.g., from about 75 to about 85). Properties such as pour point, cloud point and/or octane number may be determined after recovery of the appropriate liquid hydrocarbon fraction from the FT product, for example by cooling, condensation and/or fractionation, as described above.

As described above, positive C₂₀ ⁺The conversion level of hydrocarbons may be below 100% and thus these positive Cs are allowed₂₀ ⁺Some of the hydrocarbons are present in the FT product. To realize positive C₂₀ ⁺Complete conversion of hydrocarbons, such as complete in situ conversion to C₄-C₁₉Hydrocarbons and/or branches C₂₀ ⁺Hydrocarbons, may make the FT reaction conditions more severe, such as by increasing temperature, increasing pressure, and/or decreasing WHSV. However, it will be appreciated that according to a preferred embodiment, n-C is in the sense of being free of solid phase hydrocarbons and thus comprising a readily transportable liquid fuel fraction₂₀ ⁺Complete conversion of hydrocarbons is not a requirement to achieve complete "dewaxing" of FT products. Positive C₂₀ ⁺Incomplete in situ conversion of hydrocarbons (such as to conversion levels within the specific ranges described above) may still provide FT products in which the normal C's are formed₂₀ ⁺Sufficient components resulting from the conversion of hydrocarbons, i.e., (i) sufficient non-positive C's having a melting point below room temperature (20 deg.C.)₂₀ ⁺Hydrocarbons (e.g. branched C)₂₀ ⁺Hydrocarbon) and/or (ii) sufficient C₄-C₁₉Hydrocarbons present in the FT product up to any unconverted normal C₂₀ ⁺The extent to which hydrocarbons are dissolved at room temperature in the liquid fuel fraction recovered from the product, for example by cooling, condensation and/or fractionation, as described above.

Thus, embodiments of the present invention relate to the use of dewaxing catalysts orThe dewaxing functional component of the dual-function catalyst to increase the overall selectivity to the desired products and their yields and/or to reduce the overall selectivity to the undesired products (particularly waxes) and their yields relative to conducting the FT synthesis reaction in the absence of the dewaxing catalyst or the dewaxing functional component of the dual-function catalyst (i.e., relative to these selectivities and yields when determined using the reference FT product as described herein). For example, some or all of the wax produced by the FT synthesis reaction may be beneficially converted in situ (e.g., with a positive C as described above) using a dewaxing catalyst or a dewaxing functional component of a dual function catalyst₂₀ ⁺The conversion level of hydrocarbons) to reduce the selectivity to wax (and/or the yield of wax) relative to the selectivity when determined using a reference FT product as described herein. In representative embodiments, the selectivity to wax (and/or the yield of wax) is reduced from a value of from about 10% to about 50%, such as from about 20% to about 45%, when determined using a reference FT product as described herein, to a value of from about 0% to about 10%, such as from about 0.5% to about 5%, obtained with the use of a dewaxing catalyst or a dewaxing functional component of a dual-function catalyst. Preferably, this selectivity to wax (and/or the yield of wax) is reduced to less than about 0.5%. As described above, small amounts of wax in the FT product may be acceptable, as long as any unconverted n-C is present₂₀ ⁺The hydrocarbons and/or any hydrocarbons that normally melt above room temperature are present in an amount that is less than their solubility in the liquid fuel fraction recovered from the product (i.e., in an amount such that they can be completely dissolved in such fraction). In other exemplary embodiments, for C₄-C₁₉Liquid hydrocarbon selectivity (and/or C)₄-C₁₉Yield of liquid hydrocarbons) from a value of from about 15% to about 45%, such as from about 20% to about 35%, when determined using a reference FT product as described herein, to a value of from about 40% to about 75%, such as from about 50% to about 70%, obtained with a dewaxing functional component using a dewaxing catalyst or a dual function catalyst. For wax or C₄-C₁₉The selectivity of the hydrocarbons is based on the percentage of carbon in the CO present in the feed to the FT reactorSyngas feed to the reactor (and any co-feeds) and converted by FT, which produces wax or C, respectively, in the net FT product (excluding any recycle fraction)₄-C₁₉A liquid hydrocarbon. Wax or C₄-C₁₉The yield of hydrocarbons is based on the percentage of carbon in the CO (e.g., CO introduced into the FT reactor, whether converted or unconverted) present in the syngas feed (and any CO-feeds) provided to the FT reactor, which produces wax or C, respectively, in the net FT product (excluding any recycled portion)₄-C₁₉A liquid hydrocarbon. These (i) decrease in wax selectivity (and/or wax yield) and/or (ii) decrease in C as a result of using a dewaxing catalyst or a dewaxing functional component of a dual-function catalyst₄-C₁₉Liquid hydrocarbon selectivity (and/or C)₄-C₁₉Yield of liquid hydrocarbons) may be achieved without a significant difference between the CO conversion obtained when determined using the reference FT product and the CO conversion obtained using the dewaxing catalyst or the dewaxing functional component of the dual-function catalyst. For example, the CO conversion values obtained in both cases may be in the ranges as described above. That is, the use of the dewaxing functional component of the dewaxing catalyst or dual function catalyst generally does not significantly affect the CO conversion obtained in the FT reactor, such that the CO conversion obtained in both cases may be the same or substantially the same.

Positive C as described above₂₀ ⁺The level of conversion of hydrocarbons may be based on the "single pass" conversion achieved in one pass through the FT reactor, or otherwise the overall conversion achieved by returning a recycled portion of the FT products to the FT reactor, as described above. In the case of recycle, the reference FT product used to determine this conversion will also be obtained using the manipulated variables comprising the recycle operation.

Syngas feed

The syngas feed can be a syngas feed comprising H₂And CO and preferably has the following H₂Any gas mixture of CO molar ratio, said H₂CO molar ratio for stoichiometric production according to the FT synthesis reaction given aboveHydrocarbons are advantageous. Representative ratios encompass 2:1, such as from about 1.5:1 to about 2.5:1, from about 1.5:1 to about 2.3:1, and from about 1.8:1 to about 2.2: 1. In the product H₂And CO are generally present in a combined concentration of at least about 35 mol-% (or volume-%) (e.g., from about 35 mol-% > to about 85 mol-%), typically at least about 50 mol-% (e.g., from about 50 mol-%) and often at least about 60 mol-% (e.g., from about 60 mol-%) to about 75 mol-%). The balance of the synthesis gas product may be wholly or substantially wholly CO₂And water. Water and CO in a syngas feed₂To it H₂CO molar ratio, as described above, the H₂The CO molar ratio is an important parameter for the FT synthesis reaction.

A representative syngas feed can be derived from a feedstock containing methane and/or light hydrocarbons (e.g., C)₂-C₃Hydrocarbons or C₂-C₄Hydrocarbons) gas mixture (e.g., in steam and/or CO)₂In the presence of) because reforming generally produces hydrogen with favorable H₂Syngas at a CO molar ratio, e.g. H, in the range described hereinbefore₂CO molar ratio. Whether or not obtained from reforming, the syngas feed may be subjected to one or more pre-treatment steps (upstream of the FT reactor), such as a condensation step to remove the gas phase H₂O, or otherwise dried to remove liquid phase H₂O, for example using an adsorbent selective for water vapour, such as 5A molecular sieve. Another pretreatment step is CO₂Removal, for example by acid gas treatment (e.g. amine scrubbing). Yet another pre-treatment step is to use one or more Water Gas Shift (WGS) reaction stages to increase the hydrogen content and reduce the CO content of the syngas feed, or otherwise use one or more inverse WGS stages to decrease the hydrogen content and increase the CO content of the syngas feed. Yet another pretreatment step is the removal of H₂S and/or other sulfur-containing contaminants.

In representative embodiments, whether or not a pretreatment step is used, the CO₂Can be present in generally less than about 45 mol-% (e.g., from about 5 mol-% to about45 mol-%) and typically less than about 35 mol-% (e.g., from about 10 mol-% to about 35 mol-%) is present in the syngas feed. Water may be present in a concentration generally less than about 20 mol-% (e.g., from about 1 mol-%) and typically less than about 15 mol-% (e.g., from about 5 mol-%) and about 15 mol-%. Small amounts of hydrocarbons (e.g., unconverted hydrocarbons that break through the upstream reforming reaction) may also be present in the syngas feed. For example, it may be possible to include only C₁-C₃C of hydrocarbon₁-C₄The combined amount of hydrocarbons (e.g., the combined amount of methane, ethane, propane, and butane) may be present at a concentration of less than about 5 mol-% and typically less than about 2 mol-%.

An important source of methane is natural gas or a by-product of natural gas processing, which can be reformed to provide all or a portion of the syngas feed. For example, such methane may be present in a hydrogen-lean Pressure Swing Adsorption (PSA) tail gas, as obtained from a hydrogen production process involving steam reforming of natural gas. Such methane may also be present in the gaseous effluent from bacterial fermentation integrated with the hydrogen production process. Other sources of methane may originate from coal or biomass (e.g., lignocellulosic or charcoal) gasification, or otherwise from biomass digesters (bioglass digesterters) that produce biogas from bacterial digestion of organic waste, such as from anaerobic digestion processes and from landfills. An additional source of methane is the effluent from a renewable hydrocarbon fuel (biofuel) production process (e.g., a pyrolysis process, such as a hydropyrolysis process, or a fatty acid/triglyceride hydroconversion process). Still further sources of methane may be obtained from well heads (well heads) or effluents of industrial processes including petroleum refining processes (as refinery off-gases), electricity production processes, steel or non-ferrous metal manufacturing processes, chemical (e.g. methanol) production processes or coke manufacturing processes. All or a portion of the methane reformed to provide the syngas feed may be obtained from renewable resources (e.g., biomass), such as in the case of methane, from a process stream obtained by hydropyrolysis, as described in U.S. patent No. 8,915,981 assigned to the Gas Technology Institute. Thus, the processes described herein may be used to produce renewable hydrocarbons from a syngas feed obtained from reforming such methane. Such renewable hydrocarbons may be used to impart an overall reduction in carbon footprint associated with the synthesis of hydrocarbon-containing fuels, fuel blending components, and/or chemicals via the FT synthesis reaction as described herein. Thus, the carbon in the FT products described herein may be from non-renewable sources (e.g. natural gas) and/or renewable sources (e.g. biomass), with renewable sources imparting such reductions.

The following examples are set forth as representative of the invention. These examples should not be construed as limiting the scope of the invention, as other equivalent embodiments will be apparent in view of this disclosure and the appended claims.

Example 1

The surface area and pore size distribution of FT catalysts comprising 20 wt-% Co on an alumina support were analyzed. The surface area was 92.5m²(ii)/g (Brunauer, Emmett and Teller (BET) method based on nitrogen adsorption (ASTM D1993-03(2008)), and total pore volume is 0.14 cc/gram (Mercury porosimetry)), wherein the average pore diameter is 6.24 nanometers (nm), and wherein 14% of the pore volume is due to>Macropores at 50nm, 85% of the pore volume being due to mesopores between 2nm and 50nm, and 1% of the pore volume being due to<2nm pores.

The FT synthesis reaction is carried out in a fluidized bed reactor comprising as dense phase a mixture of (i) the FT catalyst and (ii) a dewaxing catalyst comprising 1 wt-% Ga on a ZSM-5 support. Fluidized bed reactors require higher gas flow rates to fluidize the catalyst relative to the gas flow rates used in comparable fixed bed experiments. The diameter of the fluidized bed reactor is chosen to minimize wall effects and to obtain good mixing. Mixing characteristics of fluidized bed reactors for FT Synthesis reactions because of the high Heat Release (exotherm) of the FT Synthesis reaction and also the need to avoid stratification of the two types of catalystsIs of particular importance. In these tests, the syngas feed was modeled as 60 mol-% H₂30 mol-% CO, 9 mol-% CO₂And 1 mol-% methane, to simulate typical products obtained from the reforming of methane. The conditions and results of the fluidized bed experiments compared to the fixed bed experiments using the dewaxing reactor alone are summarized in table 1 below.

TABLE 1 comparison of FT Synthesis reaction conditions

The same amount of CO was converted in the fluidized bed experiments relative to the fixed bed experiments, although a lower percentage conversion was exhibited due to the high flow of syngas feed required for fluidization. Importantly, no wax was observed in the fluid bed experiments. Overall, the results show that the fluidized bed process of the FT synthesis reaction with in situ dewaxing would be expected to work on an industrial scale.

In summary, aspects of the invention relate to methods for performing FT synthesis to produce C₄ ⁺A process and catalyst system for hydrocarbons, such as gasoline boiling range hydrocarbons and/or diesel boiling range hydrocarbons. Advantageously, the catalyst system described herein has additional activity for in situ hydroisomerization and/or hydrocracking of wax produced from the distribution of hydrocarbons obtained from the FT synthesis reaction. This not only increases the hydrocarbons (e.g., C) available for transportation fuels_4-19Hydrocarbons) yield, but also allows for alternative reactor types, such as fluidized bed reactors. Those skilled in the art, having benefit of the teachings gleaned from this disclosure, will appreciate that many changes can be made to these processes and catalyst systems in obtaining these and other advantages without departing from the scope of this disclosure. Accordingly, it should be understood that the features disclosed herein are susceptible to modification and/or substitution. The particular embodiments illustrated and described herein are for purposes of illustration only and are not limiting of the invention as set forth in the appended claims.

Claims (20)

1. For producing C₄ ⁺A process for hydrocarbons, the process comprising:

in a fluidized bed reactor containing a catalyst mixture or a dual-function catalyst and operating under Fischer-Tropsch (FT) reaction conditions, H in a syngas feed₂And CO conversion to hydrocarbons provided in a Fischer-Tropsch (FT) product, said hydrocarbons including said C₄ ⁺A hydrocarbon.

2. The process of claim 1 wherein the catalyst mixture comprises an FT catalyst comprising one or more FT active metals deposited on an FT catalyst support comprising one or more metal oxides.

3. The process of claim 1 or 2 wherein the dual function catalyst has an FT functional component comprising an FT active metal and one or more metal oxides.

4. The process according to claim 2 or claim 3, wherein the one or more FT active metals are selected from the group consisting of cobalt (Co), iron (Fe), ruthenium (Ru) and nickel (Ni).

5. A process according to claim 2 or claim 3, wherein the one or more metal oxides are selected from the group consisting of alumina, silica, titania, zirconia, magnesia and strontium oxide.

6. The process of any one of claims 1 to 5, wherein the catalyst mixture or the bifunctional catalyst is for positive C₂₀ ⁺Hydroisomerization and/or hydrocracking of hydrocarbons is active.

7. The process of any one of claims 1 to 6, wherein the catalyst mixture comprises a dewaxing catalyst comprising a dewaxing active metal deposited on a solid acidic support.

8. The process of any one of claims 1 to 7 wherein the bifunctional catalyst has a dewaxing functional component comprising a dewaxing active metal and a solid acidic support.

9. The process of claim 7 or claim 8, wherein the dewaxing active metal is selected from group 13 or group 14 of the periodic table.

10. The process of claim 9, wherein the dewaxing active metal is gallium.

11. The process of claim 7 or claim 8, wherein the solid acidic support is a zeolitic molecular sieve or a non-zeolitic molecular sieve having acid sites of at least about 15mmol/g as measured by temperature programmed desorption of ammonia (TPD).

12. The process of claim 7 or claim 8, wherein the solid acidic support is a zeolitic molecular sieve having a silica to alumina molar framework ratio of less than about 50.

13. The process of any one of claims 1 to 12, wherein the zeolitic molecular sieve is ZSM-5.

14. The process of any one of claims 1 to 13, wherein the catalyst mixture comprises:

(i) an FT catalyst comprising one or more FT active metals deposited on an FT catalyst support comprising one or more metal oxides, and

(ii) a dewaxing catalyst comprising a dewaxing active metal deposited on a solid acidic support.

15. The process of claim 14, wherein (i) and (ii) are present in the catalyst mixture in a weight ratio of from about 3:1 to about 1: 3.

16. The process of any one of claims 1 to 15, wherein the bifunctional catalyst comprises:

(i) an FT functional component comprising an FT active metal and one or more metal oxides; and

(ii) a dewaxing functional component comprising a dewaxing active metal and a solid acidic carrier.

17. The process of claim 16, wherein (i) and (ii) are present in the bifunctional catalyst in a weight ratio of from about 3:1 to about 1: 3.

18. A process for carrying out a fischer-tropsch (FT) synthesis reaction, the process comprising:

(A) under the reaction conditions, the reaction solution contains H₂And CO, flows upwardly through a fluidized bed of solid particles of a catalyst mixture that is active at the reaction conditions for:

(i) by Fischer-Tropsch (FT) Synthesis reaction, H₂And a distribution of CO to hydrocarbons, the distribution including a distribution comprising positive C₂₀ ⁺A wax fraction of hydrocarbons; and

(ii) through the positive C₂₀ ⁺Hydroisomerization and/or hydrocracking of hydrocarbons, subjecting said normal C to₂₀ ⁺Conversion of at least a portion of the hydrocarbons to normal C₄-C₁₉Hydrocarbons or branches C₄-C₁₉A hydrocarbon;

wherein the activities for (i) and (ii) are provided in combination to comprise C₄ ⁺A Fischer-Tropsch (FT) product of hydrocarbons and less than about 1 wt% of hydrocarbons that are solids at room temperature, and

(B) disengaging substantially all of the FT products from substantially all of the solid particles.

19. A process for carrying out a fischer-tropsch (FT) synthesis reaction, the process comprising:

(A) under the reaction conditions, the reaction solution contains H₂And CO, flowing upwardly through a fluidized bed of solid particles of a dual-function catalyst active at the reaction conditions for:

(i) by Fischer-Tropsch (FT) Synthesis reaction, H₂And a distribution of CO to hydrocarbons, the distribution including a distribution comprising positive C₂₀ ⁺A wax fraction of hydrocarbons; and

(ii) through the positive C₂₀ ⁺Hydroisomerization and/or hydrocracking of hydrocarbons, subjecting said normal C to₂₀ ⁺Conversion of at least a portion of the hydrocarbons to normal C₄-C₁₉Hydrocarbons or branches C₄-C₁₉A hydrocarbon;

wherein the activities for (i) and (ii) are provided in combination to comprise C₄ ⁺A Fischer-Tropsch (FT) product of hydrocarbons and less than about 1 wt% of hydrocarbons that are solids at room temperature, and

(B) disengaging substantially all of the FT products from substantially all of the solid particles.

20. The process of claim 18 or claim 19, wherein the fluidized bed of solid particles is a fixed fluidized bed, a bubble-free fluidized bed, a bubbling fluidized bed, or a slugging fluidized bed.